Primer says error but code works fine on GCC

Question

This code works fine:

    double a =2.12345;
    int b{a};            // According to primer error: narrowing conversion required
    int c(a);            //This is fine

Is it something which I am missing? For me when a float/double is assigned to int the values on left of the decimal are printed (floor value). Primer says error.

related: https://stackoverflow.com/questions/4434140/narrowing-conversions-in-c0x-is-it-just-me-or-does-this-sound-like-a-breakin — RHertel, Nov 12 '17 at 10:20
Try building it with `g++ -std=c++14` so you don't get the gnu++14 extensions. — Jesper Juhl, Nov 12 '17 at 10:41

score 4 · Accepted Answer · answered Nov 12 '17 at 10:21

Is it something which I am missing?

The unfortunate detail of compilers deviating from the standard. GCC doesn't enforce it unless you tell it that it should. Try compiling with the -pedantic-errors option.

The primer isn't wrong, it's an ill-formed program according to the C++ standard alone. But compilers may choose to accept it as an extension, such is what GCC does.

score 0 · Answer 2 · answered Nov 12 '17 at 16:32

0

Some compilers (rightfully) enforce it by default. MacOSX clang for example would return an error:

type 'double' cannot be narrowed to 'int' in initializer list [-Wc++11-narrowing]

For GCC, the option -Wconversion should generate a warning.

answered Nov 12 '17 at 16:32

Visiedo

377
5
9

Primer says error but code works fine on GCC

2 Answers2